Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 282317
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
517 PM CST WED JAN 28 2015

.SYNOPSIS...
ISSUED AT 305 PM CST WED JAN 28 2015

AT 19Z...WATER VAPOR IMAGERY SHOWED A SHORTWAVE TROUGH CROSSING THE
PLAINS WITH THE AXIS OF THE DEEP TROUGH OUT EAST JUST OFF THE EAST
COAST. LOOKING UPSTREAM...A LARGE UPPER LOW CONTINUES TO SPIN JUST
SOUTH OF THE ALEUTIAN ISLANDS...WHILE ANOTHER UPPER LOW WAS SITUATED
WEST OF BAJA CALIFORNIA. AT THE SURFACE...LOW PRESSURE WAS LOCATED
OVER FAR SOUTHEAST SOUTH DAKOTA WITH THE COLD FRONT DIPPING DOWN
INTO WESTERN OKLAHOMA. THE PRESSURE GRADIENT ACROSS THE LOCAL AREA
WAS TIGHTENED BEHIND THE COLD FRONT AND WITH DRY AIR IN PLACE AND
COLD AIR ADVECTION/SUBSIDENCE ONGOING THE BOUNDARY LAYER MIXED UP TO
700MB FOR MUCH OF THE AREA. ALONG WITH THE STRONG GRADIENT
WINDS...THE DEEP MIXING BROUGHT GUSTS UP TO 43KTS TO THE SURFACE
OVER SOUTHWEST NEBRASKA WITH WINDY CONDITIONS OBSERVED FOR ALL
AREAS. THE DEEP MIXING ALSO ALLOWED FOR TEMPERATURES TO RISE INTO
THE 60S FOR MOST AREAS...WITH RECORD OR NEAR RECORD TEMPERATURES
OBSERVED IN PLACES. WAS ALSO SEEING LIGHT RAIN SHOWERS OVER THE
PANHANDLE AND THE WESTERN SANDHILLS. HOWEVER WOULD BE SURPRISED IF
ANYTHING WAS REACHING THE GROUND AS THE LOW LEVELS WERE VERY DRY
WITH CEILINGS AT 6-9K FEET.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 305 PM CST WED JAN 28 2015

ANOTHER COLD FRONT WILL MOVE SOUTHEAST ACROSS THE FORECAST AREA
TONIGHT...BEING PUSHED BY A WEAK SHORTWAVE TROUGH WHICH WILL MOVE
THROUGH NEBRASKA THURSDAY MORNING. THIS WILL BRING COLDER AIR TO THE
REGION WITH 850MB TEMPERATURES FALLING TO -2C TO -7C BY 18Z
THURSDAY. WINDS WILL STAY HIGH TONIGHT AS THE PRESSURE GRADIENT DOES
NOT BEGIN TO RELAX UNTIL LATER TONIGHT AND THURSDAY MORNING. WITH
THE WINDS AND INCREASED CLOUD COVER OVERNIGHT WILL KEEP TEMPERATURES
FROM DROPPING TOO FAR DESPITE THE COLDER AIR MOVING INTO THE AREA.
KEPT LOWS IN THE MID 20S TO LOW 30S...BUT IF WINDS DROP OFF AT ALL
THESE MAY BE TOO WARM AND MAY NEED TO BE RE-EVALUATED...ESPECIALLY
OVER THE WESTERN PART OF THE FORECAST AREA WHERE WINDS MAY DROP OFF
EARLIER. SEEING SLIGHT WARM ADVECTION THROUGH THE AFTERNOON THURSDAY
AS THE SHORTWAVE PASSES AND WEAK RIDGING ALOFT BEGINS BUILDING IN
AGAIN. THIS INCREASE IN TEMPERATURES WILL BE MINIMAL THOUGH...WITH
850MB TEMPERATURES STAYING BELOW 0C. FORECAST MODELS ARE INDICATING
BOUNDARY LAYER MIXING TO AROUND 850MB WHICH WOULD KEEP HIGHS IN THE
30S TO MID 40S.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 305 PM CST WED JAN 28 2015

TRENDED LOWS A LITTLE COOLER FOR THURSDAY NIGHT AS LATEST MODEL
RUNS HAVE COME IN SLOWER WITH A SFC HIGH SLIDING JUST NORTH OF THE
AREA. AS MENTIONED IN PREVIOUS FORECASTS A LOW LEVEL JET STILL
DEVELOPS DURING THE PERIOD...HOWEVER AT THE MOMENT IT LOOKS TO BE
MORE TOWARD EARLY FRIDAY MORNING WHICH MAY MIX DOWN WARMER TEMPS
TO THE SFC TEMPS BY SUNRISE ACROSS WESTERN SANDHILLS. SPLIT FLOW
PATTERN ALOFT DEVELOPS OVER THE CENTRAL PLAINS AS WESTERN CONUS
TROUGH BEGINS TO CUT OFF NEAR THE CA/MEXICAN BORDER. WEAK MID
LEVEL WAA AND SOUTHERLY WINDS RESULT IN A MEAGER WARM UP FROM
THURSDAY INTO THE MID 40S TO LOW 50S.

12Z GFS/NAM/EC AND ENSEMBLES HAVE ALL TRENDED MUCH DRIER ACROSS
NEBRASKA FOR SATURDAY INTO SUNDAY. THIS IS A SIGNIFICANT CHANGE FROM
THE 00Z SOLUTIONS OF TUESDAY NIGHT WHICH BLANKETED MOST OF THE AREA
WITH SEVERAL INCHES OF SNOWFALL. THE PREVIOUSLY MENTIONED UPPER
LEVEL LOW CUTTING OFF NEAR THE MEXICO BORDER STREAMS AMPLE AMOUNTS
OF PACIFIC MOISTURE NORTHEASTWARD INTO THE CENTRAL PLAINS BY
SATURDAY. HOWEVER...THE NORTHERN STREAM PV MAX...ROBUST IN PREVIOUS
RUNS...IS NOW PROGGED TO BE QUICKER AND MUCH LESS AMPLIFIED AS IT
MOVES THROUGH THE FAST NORTHWEST FLOW AND SHEARS MOST OF THE PACIFIC
MOISTURE OFF TO OUR SOUTH AND EAST. THE GFS AND EC BOTH DROPPED
THEIR LAYER PWAT VALUES FOR LBF BY ALMOST HALF AN INCH ON SATURDAY.
THE NORTHERN AND SOUTHERN STREAMS PHASE INTO CONFLUENT FLOW ALOFT
OVER THE AREA...MAKING IT TOUGH TO PRODUCE ANY QPF. THE RESULT IS A
MUCH DRIER FORECAST...HOWEVER DID NOT WANT TO COMPLETELY CUT OUT
POPS UNTIL THE MODELS SHOW MORE RUN TO RUN CONSISTENCY.

A STRONG COLD FRONT DROPS SOUTH THROUGH THE CWA LATE SATURDAY.
BREEZY NORTH WINDS DUE TO STRONG PRESSURE RISES BEHIND THE FRONT
SHOULD PROMOTE SOME DEGREE OF MIXING AND KEEP TEMPS WITHIN THE
TEENS SATURDAY NIGHT. MODELS ARE SHOWING WEAK ISENTROPIC LIFT
BEHIND THE FRONT AND GENERATING QPF OVER PARTS OF THE CWA SATURDAY
NIGHT...HOWEVER MOISTURE WILL NOT BE AT A PREMIUM AND ANY SNOWFALL
ACTIVITY SHOULD BE LIGHT AND SCATTERED. TEMPERATURES ON SUNDAY
WILL STRUGGLE AS H85 TEMPS COOL TO -10C TO -16C ACROSS THE
CWA....KEEPING MOST OF THE AREA BELOW FREEZING THROUGH THE DAY.

FORECAST LOOKS MAINLY DRY WITH NEAR TO JUST ABOVE NORMAL TEMPS FOR
THE FIRST HALF OF NEXT WEEK. THE UPPER LEVEL PATTERN REVERTS BACK
TO THE FAMILIAR WEST COAST RIDGE AND STRONG LOW OVER THE HUDSON
BAY...KEEPING NORTHWEST FLOW IN PLACE OVER THE CENTRAL PLAINS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 516 PM CST WED JAN 28 2015

WINDY CONDITIONS WILL PERSIST INTO THIS EVENING...THEN GRADUALLY
WILL FALL OVERNIGHT. SOME AREAS WILL LIKELY SEE GUSTY CONDITIONS
REMAIN THROUGH MUCH OF THE NIGHT...GENERALLY ALONG AND EAST OF A
LINE FROM KVTN TO KLBF. THE PRESSURE GRADIENT DOES WEAKEN GOING
THROUGH THE MORNING THURSDAY SO THE FORECAST TRENDS WITH
DECREASING WINDS. THE MODELS ARE SHOWING AN INCREASE IN LOW LEVEL
MOISTURE OVERNIGHT...SO THINKING A PERIOD OF MVFR STRATUS WILL BE
OBSERVED ACROSS THE AREA LATE TONIGHT...WHICH LOOKS TO MIX OUT IN
THE MORNING.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...BROOKS
SHORT TERM...BROOKS
LONG TERM...MARTIN
AVIATION...ROBERG







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